The present invention relates to a method of manufacturing tuner chassis and, more particularly, to method of manufacturing the chassis for high frequency tuners such as UHF tuners.
The prior-art method of manufacturing high-frequency tuners is as follows. Initially, a chassis housing is formed by bending a material stamped from a steel plate. Also, shield plates for partitioning the interior of the housing into a plurality of cavities are stamped from a steel plate. These component parts are assembled to obtain an eventual chassis. The surface of this eventual chassis is then electroplated with copper and then with tin. In the high-frequency tuner, it is usually desired that the individual cavities defined by shield plates be perfectly shielded with respect to one another. In order to obtain perfect shielding, it has been the practice to braze the abutting portions of the shield plates and housing with copper. This is carried out by putting the chassis assembly together with copper pieces placed adjacent to the abutting portions into a high temperature heating furnace. The heating temperature of the furnace is set to about 1,000.degree. C., at which temperature the copper pieces are fused to join together the abutting portions.
In the above prior-art method of manufacture, however, a long processing time is required due to the heating process in the high temperature heating furnace. In addition, perfect sealing of the abutting protions cannot be obtained in practice even with the above brazing process, and leakage of high frequencies are prone to occur. Further, since the assembly is plated with tin, "wiskers" of tin are liable to result, giving rise to an accident of shorting between circuits.